BPSK_Signaling.m

%Shift Keying Techniques - BPSK
clc; clear all; close all;

M = 2;                                      %Alphabet size
N = input("Enter the number of symbols:")   %Number of symbols
nb = log(M)/log(2)                          %Number of bits/symbol

%Transmitter
%Bit generation
b = randi([0 1],N*nb,1);                    %Random binary bits
bs = b; bs(bs==0)=-1;                       %converting logical to electrical
xs = bs;
scatterplot(xs);

SNRdB = 1:7:15
for ii=1:length(SNRdB)
    SNRii = SNRdB(ii)
    rn = awgn(xs, SNRii, 'measured');
    figure; plot(real(rn), imag(rn),'b.',bs, imag(b), 'ro'); legend('recieved', 'ideal')
    xlabel("Real"); ylabel("Imaginary")
    title(['BPSK constellation at SNR=' num2str(SNRii), 'dB']); axis([-5.5 5.5 -1.5 1.5])

    bcat=real(rn); bcat(bcat>=0)=1; bcat(bcat<0)=0;

    snr = 10^(SNRii./10);
    Eb_by_No = snr/2;
    Eb_by_No_dB(ii) = 10*log10(Eb_by_No);
    BER_th(ii) = 1/2*erfc(sqrt(Eb_by_No));
    BER(ii) = length(find(b~=bcat))/(N*nb);
    EVM = sqrt((sum(bs-real(rn).^2))/N)/var(b)*100;
    EVMdB(ii)=20*log10(EVM);
end

figure;
semilogy(Eb_by_No_dB, BER, 'b-',Eb_by_No_dB, BER_th, 'b*'); axis([0 12 10^-7 1]);grid on;
xlabel('E_b/N_o(dB)'); ylabel('Bit Error Probability (P_e)'); title('BER performance of BPSK');